Bearing apparatus



June 21, 1960 P. c. WARNER BEARING APPARATUS Filed Aug. 10, 1959 LOWEXPANSIQN MQTERIAL mm A. F N O 2 i 5 Ha W 3 l WWI n/ M W m w M m m R I PJ .ll... 0-

E I A El HIGH EX FANS/ON MHT'ERIA L INVENTOR PAUL C. WARNER UnitedStates Patent BEARING APPARATUS Paul C. Warner, Media, Pa., assignor toWestinghouse Electric Corporation, East Pittsburgh, Pa., 21 corporationof Pennsylvania Filed Aug. 10, 1959, Ser. No. 832,540

4 Claims. (Cl. 308-73) This invention relates to bearings, moreparticularly to the type of bearing which is slidably disposed relativeto the runner or shaft element associated therewith and operable with alubricating fluid film disposed therebetween.

One of the main objects of the invention is to provide an improvedbearing structure of this type, which is easily manufactured whilemaintaining the extremely close tolerances required in high performancebearing structures of this type.

It is well known in the art, that for optimum performance, maximumseparation of the relatively slidable surfaces must be maintained forany prescribed load. Such separation is maintained by the lubricatingfluid film thickness. Many shapes have heretofore been proposed forobtaining maximum fluid film thickness between the relatively slidablesurfaces of the bearing struc- I ture. However, as well known in thebearing art, the stepped or wedgeshaped bearing is one of the'mosteffective thus far known types. Such wedge shaped bearing structures,when heavily loaded, may provide a lubricating film thickness of only.00025 to .0005 inch. Accordingly, it will be obvious that with bearingstructures designed to operate with such thin lubricating fluid films,minimum variations in the surface from the desired contour .must bemaintained.

The wedge shaped bearing structure includes a bearing member arranged toslidably support a runner eleinent movable therepast in a path relativeto the former with a lubricant film formed therebetween. To maintain.the thickness of the fluid film at the maximum value for a prescribedload, the bearing member is provided with a carefully finished bearingsurface having a leading surface portion and a trailing surface portionoffset about .002 to .0005 inch with relation to each other and forminga shoulder at the junction therebetween. Accordingly, in operation, thebearing structure maintains a lubricating fluid film which is of greaterthickness adjacent the leading portion than the thickness of the fluidfilm adjacent the trailing portion, and is elfective to main tain thethickness of the latter film at a larger value than attained with otherknown arrangements for any prescribed load.

However, manufacture of a wedge shaped bearing of the type describedabove is exceedingly diificnlt because of the extreme precision requiredin finishing the bearing surfaces for proper operation. Accordingly, itis a further object of the invention to provide a wedge shaped bearingstructure which may be more readily manufactured and maintained withinthe required manufacturing tolerances.

A more specific object of the invention is to provide a wedge shapedbearing structure in which the bearing member is formed of'two materialshaving diiferent coefiicients of expansion and arranged in such a mannerthat the bearing surface may define a continuous and uninterruptedsurface at normal room temperatures, while Patented June 21, .1960

expanding when heated to operating temperatures to provide the relativeoifset required between the leading and trailing surface portions of thebearing member.

In accordance with the invention, the bearing member is provided with abacking member and a facing member formed of materials having differentcoe'fiicients of expansion. When the backing member is made of a lowexpansion material and the facing member is made of a high expansionmaterial, the backing member is pro- 'vided with stepped interfacialsurface portions having'a shoulder so formed therebetween and of such aheight that when the facing member is applied thereto and finished to asmooth continuous surface contour, the facing member has a leadingbearing surface portion of less thickness than its trailing surfaceportion at normal atmospheric temperatures. Accordingly, the hearing maybe easily finished to the required tolerances by ordinary manufacturingprocesses. I

In operation, as the bearing member becomes heated to its normaloperating temperature, the thermal growth or expansionof thecompositeleading portion of the bearing structure is less than that ofthe trailing portion of the bearing structure in a direction normal tothe surface of the runner member, thereby causing a discontinuity in thetwo surface portions in the region adjacent the shoulder of the backingmember and imparting; the desired wedge shape to the eifective bearingsurface.

Further, in accordance with the invention, when the: backing member isformed of high expansion material and the facing member is formed of lowexpansion ma-- terial, the shoulder in the interfacial surface of theback-- ing member is reversed, thereby causing the thickness of the lowexpansion material at the leading surface por-- tion of the bearingsupport to be larger than the trail-- ing surface portion. Uponexpansion, a discontinuity is attained in the surface of the facingmember due to the greater degree of expansion of the composite trail--ing portion, in a manner similar, but converse, to the above describedarrangement.

The above and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing forming a part of this application, inwhich:

Figs. 1 and 2 are diagrammatic views illustrating the wedge shapedbearing structure of the prior art;

Figs. 3 and 4 are diagrammatic views illustrating wedge shaped bearingstructures formed in accordance with the invention;

Fig. 5 is an axial sectional view taken on line V--V of Fig. 6 andshowing, in highly simplified form, a thrust bearing of the doubleacting type having the invention incorporated therein;

Fig. 6 is a cross-sectional view taken on line VIVI of Fig. 5;

Figs. 7 and 8 are enlarged sectional views of a thrust shoe taken onlines VII--VII and VIIIVIII, respectively, of Fig. 6;

Fig. 9 is an elevational view of a pivoted shoe journal bearingembodying the invention;

Fig. 10 is an enlarged sectional view taken on line XX of Fig. 9; and

Fig. 11 is an end view of a rigidly supported journal bearingincorporating the invention.

Referring to the drawing in detail, in Figs. 1 and 2 there is shown astepped or wedge shaped bearing 10 formed in accordance with the priorart and arranged to slidably bear against a runner element 11 movablethere'- past in the direction of the arrow 12. The bearing member 10 isprovided with a stepped facing portion including a leading surfaceportion 13 of smooth contour and a trailing surface portion 14 of smoothcontour. The lead ing and trailing surfaces 13 and 14 are ofisetrelative to each other by a shoulder portion 15; The height of theshoulder portion 15 has been greatly exaggerated, for clarity ofillustration, since in practice, it is on the order of about .00025 to.602. inch. Since the runner element H has a smooth and continuoussurface 16, the, lubricating fluid film disposed between the bearingand, runner elements is thicker in the leading portion than in thetrail.- i'ng portion. Accordingly, in a manner well known, in the, art,when the bearing is subjected to a load W urging it towards the runnerelement 11, the minimum thiclc ness of the lubricating fluid film (thatis the fluid film adjacent the trailing portion 14) is maintained at ahighly suitable and uniform value for the bearing.

However, it will be noted that since the bearing member 1'0 is providedwith a unitary facing portion including the leading portion 13, theshoulder and the. trailing portion 14, extreme care and precision arerequired for itsmanufacture. Further, in operation under temperature,temperature gradient and load, the bearing memher is subject todistortion suificient to change the shape and thickness of the fluidfilm with adverse effects such as localized loss of fluid film withattendant rapid wear.

In Fig. 3 there is shown abearing member formed in accordance with theinvention and including a. substantially rigidbacking member 21 of lowexpansion material and 21 facing member 22' of high expansion facingmaterial connected in intimate back-to back relation with eachother. Thebearing member 20 is cooperatively associated with a runner member '23,movable therepastin the direction indicated by the. arrow, which runnermember may be similar to the runner member 11 shown in Fig; 1 and havinga smooth continuous surface 24.

Considering the bearing member 20 at normal atmospheric temperatures, asillustrated by the solid lines, the backing member 21' has a leadinginterfacial surface portion 2S disposed in offset relation with thetrailing interfacial surface portion 26 and having a shoulder portion 27of predetermined height disposed between the two surfaces; The leadingand trailing surfaces and 26 are so disposed that when the facing member22 is applied thereto and finished to provide a smooth and continuousbearing surface 28, the; leading portion 29 of the facingmember'issubstantially thinner than the thickness of the trailingportion 31% Accordingly, the bearing surface. 2% may be easilyandaccurately machined to its smooth and continuous contour by the usualmachining processes, while maintained at substantially normalatmospheric temperatures;

During operation, the bearing member 29 becomes heated toits normaloperating temperature, which temperature is substantially higher thanthe normal ambient temperatures. As the temperature of the bearingmember increases, the expansion of the backing member 21 in a directionnormal to the direction of movement of the runner member 23 is of arelatively small order. Further, the differential expansion of thebacking member in this direction between its leading portion 25 andtrailing portion 26- may be of a considerably smaller order. However,the differential expansion between the leading portion 29 and trailingportion 39 of the facing member is of a considerably higher order than,that of the backing member, sothat the diflerence or relative expansionbetween the composite leading portion 25, 29 and the composite trailingportion 26, 30- of the bearing member 20 attains a value on the order offrom .00025 to .002 inch, thereby providing a; discontinuity in thehearing surface 28 and forming an effective bearing surface (indicatedby the dot-dash line 31) which approaches the Wedge shape of the bearingmember 10 illustrated in- Figs. 1- and 2. Accordingly, the fluid film 32residing between the eifectivebearing surface 31 and the surface 24ofthe runner member attains the shape illustrated by the stippling. Morespecifically, the thicknessof the fluid film 32: is greater in. theleading portion of the bearing part all of the desirable qualities tothe bearing of the stepped bearing structure 10, illustrated inconjunction with the prior art in Figs. 1 and 2, but at considerablyless expense and with greater ease of manufacture. The height of theshoulder 27 is dependent on the coefficient of expansion of thematerials selected for the backing and facing members. However, it isconsiderably larger than the height of the step in the bearing surfaceand may be on the order of inch. In this connection, it will. be notedthat since the offset surfaces 25 and 26 are provided in the backingmember, and the shoulder 27 is relatively large, the extreme precisionrequired for bearing surfaces is not required in the manufacture of theoffset surfaces 25 and 26 and the shoulder 27.

In Fig. 4 there is shown a bearing member 35 operatively associated witha runner member 36 movable therepast in a path indicated by the arrow.The bearing member 35 is, similar. to the bearing member 20 shown in,Fig. 3 and differs therefrom in the selection of materials employed inits manufacture. More. specifically, the bearing member 35' has abacking member 38' formed of high expansion material and a facing member39 formed of low expansion material bonded thereto in any suitablemanner. In this embodiment, since the appreciable expansion occurs in.the backing member 38', the backing member is formed with an interfacialleading surface 40. and a. trailing intcrfacial surface portion 41offset relative to each other in a reverse manner to that shown. in.Fig. 3, so that, when the facing member 39 is applied to the backingmember 38, the thickness of. the leading portion 42 of the facing memberis greater than the thickness of the trailing portion 43, as illustratedin solid" lines.

During operation, in a manner similar to that described in conjunctionwith the embodiment shown in Fig. 3, the relative expansion of the highexpansion material in a direction normal to the surface of the runnerelement 36 is greater in the trailing portion. 41 than in theleading-portion 40" of the backing member 35, thereby deforming thesurface of the facing member 39 to provide an effective bearing surfaceof stepped shape (in.- dicated by the dot-dash lines 44), similar to theeffective bearing surface 31 attained with the embodiment shown in Fig.3.

In view of the above, it will now be understood that the invention maybe successfullypracticed by combining a high expansion material with alow expansion material, regardless of whether the backing member or thefacing member is formed of the low expansion mate'- rial. Such lowexpansion materials and high expansion materials suitable for bearingmanufacturing have been thoroughly explored in the prior art and neednot be specifically listed herein.

Figs. 5 and 6' show the invention incorporated in a thrust bearing 50.The thrust bearing 50 is of a well known type and comprises a housing 51encompassing a rotatable shaft 52 having an annular collar 53 fortransmitting the thrust of the shaft 52 in either axial direction to apair of annular rows 54 and 55 of bearing shoes. Since the bearingstructure 50 absorbs the thrust of the collar 5-3 in either axialdirection, the row 540.1. bearing shoes and its associated structure maybe idendeal to the row: 55' of bearing shoes and its associatedstructure.

As best shown. in Fig: 5', the annular row 54- ofbearingshoes comprisesa plurality-of bearingshoes 56' disposedv in abutment with thejuxtaposed radial face 57 of the thrust collar 53 andmaintained inproper posi-'- tion relative. thereto by an equalizing;- ring member 58positionedwithin an: annular inner housing- 59 in such a manner" as toprovide equal pressure upon the hearing shoes: 56. The inner housing 59may be adjustably arranged within the: outer. housing 51 by' anysuitable means. (not: shown) as: well.- known. in; the; are.

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In accordance with the invention, each of the bearing shoes 56 comprisesa backing member 60 and a facing member 61 bonded or otherwise joinedthereto. In this embodiment, the backing member 60 is formed of a lowexpansion material while the facing member 61 is formed of a highexpansion material. Referring to Fig. 6, each of the bearing shoes 56has a leading portion 62 and a trailing portion 63 with respect to thedirection of rotation of the shaft 52 as indicated by the arrow. Thebacking member 60, as best shown in Fig. 8, has a leading portion 64 anda trailing portion 65 which are offset relative to each other. Thefacing member 61 is provided with a flat bearing surface 66 adapted tocooperate .with the collar surface 57 with a lubricating fluid filmresiding therebetween. The leading portion 64 of the backing member 60is of arcuate shape (Fig. 6) and extends toward the collar surface 57 to-a greater degree than the trailing portion 65, so that the thickness ofthe facing member 61 is less at the leading portion 62 than at thetrailing portion 63 of the shoe. In this embodiment, the shoulder 67defined by the leading and trailmg portions 64 and 65 of the backingmember 60 is of arcuate shape, as shown in Fig. 6.

A ccordingly, in a manner similar to that described in con unction withthe embodiment shown in Fig. 3, at normal atmospheric temperature thebearing surface 66 is substantially fiat, as illustrated in solid linesin Figs. 7 and 8. However, when the bearing attains its normal operatingtemperature, the relative expansion between the composite leadingportion of the facing member and the composite trailing portion of thefacing member will cause the bearing surface 66 to attain the wedgeshape indicated by the dot-dash lines 68. In this case however, theeifective bearing surface 68 is offset as indicated by the dotted linesin Fig. 6, thereby to provide a minimum fluid film thickness not only inthe region intermediate the trailing surface of the shoe and the collarsurface 57 but also along the lateral surfaces of the shoe.

Figs. 9 and show the invention incorporated in a pivoted shoe journalbearing 70, of a type generally well known in the art, for rotatablysupporting a journal 71. The bearing structure 70 includes a pluralityof arcuate bearing shoes 72, for example four, disposed within a tubularhousing 73 and supported therein for pivotal movement by axiallyextending pins 74 disposed intermediate the shoes and the housing asbest shown in Fig.

10. With this arrangement, thebearing shoes 72 are free to pivot aboutthe pins 74 to a limited degree to accommodate the contour of thejournal 71 with the least possible interference.

In accordance with the invention, each of the shoes 72 is provided witha backing member 75 having a leading mterfacial surface portion 76 and atrailing interfacial surface portion 77 in offset relation to each otherand having an axially extending shoulder 78 formed therebetween. Thebearing shoes 72 are further provided with a facing member 79 bonded tothe backing member 75 and having a cylindrical bearing surface 80 whichis substantially smooth and continuous at normal ambient atmospherictemperatures. The backing member 75 is of low expansion material whilethe facing member 79 is of high expansion material. Accordingly, in amanner similar to that described in conjunction with the embodimentshown in Fig. 3, the leading portion 81 of the facing member is ofsubstantially thinner radial thickness than the thickness of thetrailing portion 82. However, as the bearing shoes 72 attain theirnormal working temperature, an effective wedge shaped bearing surface isattained, as indicated by the dot-dash lines 83-. In this embodiment,the shoulder 78 extends substantially in a direction parallel to theaxis of the journal 71.

Fig. 11 shows the invention incorporated in a journal bearing 90 of therigidly supported shoe type for rotatably supporting a cylindricaljournal 91. In this embodiment,

there is provided a pair of semi-annular bearing members 92 firmly heldwithin a tubular outer housing 93. Here again, each of the bearingmembers 92 is provided with a backing member 94 of high expansionmaterial and a facing member 95 of low expansion material. The backingmembers 94 are provided with alternately disposed thick and thinportions 98 and 99 forming axially ex tending shoulders 100 at theirjunctions.

The facing member 95 is joined or otherwise firmly attached to theassociated backing member 94 and finished to provide a smooth andcontinuous bearing surface 101. The bearing surface 101 in this case issubstantially cylindrical in shape. As the bearing 90 attains its normaloperating temperature, the shape of the bearing surface 101 is modifiedto provide a stepped effective bearing surface, as indicated by thedot-dash lines 102,

- thereby providing alternately thick and thin film spaces 103 and 104,respectively, with reference to the direction of travel of the journal91.

It will now be seen that the invention provides a bearing structurewhich attains the highly desired wedge or stepped shape in operation foroptimum efficiency, yet which can be manufactured economically andexpeditiously by the usual machining processes.

It will further be seen, that the invention lends itself to theprovision of bearing structures employing present backing and facingmaterials arranged to take advantage of the thermal expansion propertiesof the two members.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit there of.

What is claimed is:

1. A bearing member for a runner element movable in a-path relative tothe former with a lubricant film formed therebetween, said bearingmember comprising a backing member and a facing member connected inintimate back-to-back relation with each other, said backing memberhaving a leading portion of uniform thickness and a trailing portion ofuniform thickness, the thickness of said trailing portion beingdifferent than the thickness of said leading portion, said leading andtrailing portions 1 jointly defining a shoulder of predetermined heightextending transversely to the path of movement of said runner element,and said facing member having a leading portion and a trailing portioncoextensive with said backing member and defining a smooth andcontinuous bearing surface at a first temperature, said backing memberbeing formed of a material having a different coeificient of expansionthan said facing member, whereby at a second and higher temperature thedifferential expansion between said backing member and said facingmember effects a discontinuity in the bearing surface of said facingmember in the region adjacent said shoulder.

2. A hearing member for a runner element movable in a path relative tothe former with a lubricant film formed therebetween, said bearingmember comprising a substantially rigid backing member and a facingmember connected in intimate back-to-back relation with each other, saidbacking member having a smoothly faced leading portion and a smoothlyfaced trailing portion, said leading and trailing portions being offsetrelative to each other and jointly defining a shoulder of predeterminedheight extending transversely to the path of movement of said runnerelement, and said facing member having a thin leading portion and athick trailing portion coextensive with said backing member and defininga smooth and continuous bearing surface at normal atmospherictemperature, said backing member being formed of a material having alower coefficient of expansion than said facing member, whereby withincreasing temperatures the trailing portion of said facing memberincreases in thickness at a faster rate than the leading portion of saidfacing member and projects toward said runner to 1 decrease. thethickness of the lubricant film formed therebetween.

3. A bearing shoe for absorbing the thrust of a. runner element slidablymovable relative to the former-with a lubricant film formedtherebe-tween, said bearing shoe comprisinga substantially rigid backingmember and a facing member connected in intimate backrto-back relationwith each other, said backing member having a: flat leading, portion anda flat trailing portion, said leading. and trailing portions beingoifset relative to each other and jointly defining a. shoulder ofpredetermined height, extending transversely to the path of movement ofsaid runner element, said facing member having a leading portion and atrailing portion. coextensive with said backing member and defining acontinuous flat bearing surface at normal atmospheric temperature,saidbacking member being formed of a material having a differentcoefiicient of expansion than said facing. member, whereby at normaloperating temperatures the differential expansion between said backingmember and said facing member effects movement of said trailingportionof the facing member toward said runner element.

4. A bearing member for a runner elementmovable in a path relative tothe former with a lubricant film formed therebetween, said bearing,member comprising a backing member'and a facing member bonded. to eachother in intimate back-tdbackfrelation, said backingmemberhavingal'eading. portion and a trailing portion each of. which has asmooth continuous surface but offset relative to each other to define ashoulder extending. transversely to the path of movement of the runnerelement, said facing member having a leading portion. and a trailingportion of greater thickness than the former, said. facing having asmooth and continuous external surface at a first temperat'ure,psaidbacking member beingformed of a material having a different coefficientof expansionthansaid facing material, whereby at a second and highertemperature the differential expansion between said backing member andsaid facing member effects a discontinuity in the surface of said facingmember and causes the, surface of the trailing portionof the facingmember to project beyond the surface of the leading portion of thefacing member.

References Cited" in the file of this patent UNITED STATES PATENTS2,363,430 Meldahl Nov. 21', 1944 than.

